JP2775892B2 - Two-terminal element type liquid crystal display - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a two-terminal element type liquid crystal display device (hereinafter, abbreviated as “two-terminal LCD”) used for a liquid crystal display or the like.

[Conventional technology]

In recent years, development of a high-definition display element having a lot of image information has been actively performed. Two-terminal LCD with pixel electrode and two-terminal element (diode such as MIM, varistor, etc.)
With regard to (1), it is necessary to reduce the area of both the pixel electrode and the two-terminal element in the area of one pixel in achieving higher definition. However, miniaturization of the area occupied by the two-terminal element has a limit as device characteristics. Further, it is necessary to increase the aperture ratio in order to obtain a bright display screen, and the gap between the pixel electrode and the wiring is reduced in order to increase the area of the pixel electrode.

As a result, capacitive coupling using the liquid crystal layer as a dielectric layer between the pixel electrode and the wiring is increased, and the potential of the pixel electrode when not selected is changed under the influence of the signal voltage on the data bus line. That is, it is necessary to make the step width of the voltage when gradation display is performed depending on the magnitude of the voltage larger than the voltage fluctuation width, and the gradation display capability is reduced. For this reason, in order to perform high gradation display, a structure for suppressing a voltage fluctuation of the pixel electrode is required.

FIG. 3 (a) is a view showing the structure of a conventional two-terminal LCD, and FIG. 3 (b) is a cross-sectional view taken along the line AA 'in FIG. 3 (a). In the figure, 1 is a transparent insulating substrate, 2 is a two-terminal element, 3 is a pixel electrode, and 4 is a data bus line.
As shown in FIG. 1, the conventional two-terminal element matrix array has a structure in which a data bus line 4 and a pixel electrode 3 are arranged close to each other. Therefore, the above-described capacitor C _SD having a liquid crystal layer as a dielectric layer between the data bus line 4 and the pixel electrode 3 is used.
Occurs. The data bus line 4 and the pixel electrode 3 are alternately capacitively coupled to each other via the capacitor _CSD, and the voltage of the unselected pixel electrode 3 is easily affected by the change in the image signal voltage on the data bus line 4. To fluctuate. Therefore, it is necessary to make the step width of the voltage larger than the voltage fluctuation width according to the normal method of performing gradation display depending on the magnitude of the voltage, and it is difficult to perform many gradation displays. In addition, the coupling capacitance between pixels adjacent in the row direction also poses a problem when performing high-definition display with a reduced step width of gradation display.

[Problems to be solved by the invention]

As described above, in the structure of the conventional two-terminal -LCD, capacitance C _SD between the pixel electrodes and the data bus lines increases as becomes high definition two terminals -LCD large number of pixels, the potential of the order pixel electrode 3 the capacitance C via the _SD there is a problem that is easily affected by changes in the signal voltage on the data bus line, two terminals that can multi-tone display with high definition -
It is difficult to make LCDs.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the capacitance between a pixel electrode, a data bus line, and a pixel electrode, and prevent a voltage change of the pixel electrode due to a change in a signal voltage on the data bus line.

[Means for solving the problem]

The two-terminal device 2 and the pixel electrodes 3 are arranged in a matrix array on the transparent insulating substrate 1, the data bus lines 4 are arranged in the column direction of the pixel electrodes, and the transparent insulating substrate 1 and the opposing transparent electrode substrate 5 are arranged. In the liquid crystal display device with the liquid crystal layer 6 interposed therebetween, an earth line 8 is provided on the data bus line 4 with a low dielectric constant interlayer insulating layer 7 interposed between the pixel electrodes 3 and the pixel electrodes 3 adjacent in the row direction. A two-terminal element type liquid crystal display device, wherein an electrode having a pixel width is provided and connected to the ground line.

[Action]

If the earth line 8 is connected to the ground potential, the data bus line 4 is shielded and almost no coupling capacitance occurs between the pixel electrodes. Therefore, the voltage of the pixel electrode 3 is not affected by the data bus line voltage. In addition, in order to reduce the load on the liquid crystal driving driver to reduce the voltage consumption and to suppress the waveform dulling of the image signal due to the capacitive load on the data bus line, a low dielectric constant made of a low dielectric constant material having a relative dielectric constant of 3 to 5 is used. An interlayer insulating layer 7 was provided. As a result, the voltage of the pixel electrode 3 is not affected by the voltage of the data bus line,
It is possible to control the gradation display voltage in smaller voltage increments.

Example 1 FIGS. 1 (a) and (b) and FIGS. 2 (a) to 2 (b)
An embodiment of the present invention will be described with reference to FIG.

On the transparent insulating substrate 1 on which the pixel electrodes 3 and the data bus lines 4 are formed (FIG. 2A), a silicon oxide film SiO ₂ as a low dielectric constant insulating material is formed to a thickness of 0.5 μm by a plasma CVD method. Patterned by photolitho process, CF ₄ by RIE
Dry etching using gas to obtain low dielectric constant interlayer insulating layer 7
Was formed (FIG. 2 (b)). Then aluminum (A
1) was formed into a film having a thickness of 2 μm by sputtering, patterned by a photolithography process, and etched to form an earth line 8 (FIG. 2C). Next, 0.5 μm of SiO ₂ was formed as a protective film by a sputtering method, and was patterned by a photolithographic process (FIG. 2D). Thereafter, liquid crystal was injected into the gap between the transparent insulating substrate 1 and the opposing transparent electrode substrate 5 to produce a two-terminal LCD (see FIGS. 1A and 1B).

In the two-terminal element matrix array obtained as described above, the coupling capacitance C _SD between the data bus line and the pixel electrode is obtained.
Is sufficiently small, and the potential of the pixel electrode is hardly affected by the signal voltage on the data bus line, so that display with more gradations can be performed.

〔The invention's effect〕

As described above, according to the present invention, the voltage fluctuation of the pixel electrode due to the capacitive coupling can be suppressed, and the crosstalk can be prevented. Therefore, finer voltage control of the pixel voltage becomes possible, and multi-gradation display becomes possible.

[Brief description of the drawings]

1 (a) and 1 (b) are explanatory views of the configuration of the present invention, where (a) is a plan view and (b) is a view taken along line AA 'in (a).
2 (a) to 2 (d) are cross-sectional views of the part shown in FIG.
(B) is an explanatory view of a conventional two-terminal LCD. DESCRIPTION OF SYMBOLS 1 ... Transparent insulating substrate 2 ... 2 terminal element 3 ... Pixel electrode 4 ... Data bus line 5 ... Opposing transparent electrode substrate 6 ... Liquid crystal layer 7 ... Low dielectric constant interlayer insulating layer 8 ... Earth Line 9: Protective film 10: Opposite transparent electrode

Claims (1)

(57) [Claims] 1. A two-terminal element and a pixel electrode are arranged in a matrix array on a transparent insulating substrate, and a data bus line is arranged in a column direction of the pixel electrode. In a liquid crystal display device sandwiching a liquid crystal layer, an earth line is provided on the data bus line via a low dielectric constant interlayer insulating layer, and further, an electrode having a pixel width is provided between pixel electrodes adjacent to the pixel electrode in a row direction. A two-terminal element type liquid crystal display device connected to the earth line.